The Case for Simplicity

Transcription

1 Return to Session Menu DYNAMIC POSITIONING CONFERENCE October 15-16, 2013 POWER SESSION The Case for Simplicity Sean M. Hickey Loch Caillte Consulting

2 DYNAMIC POSITIONING CONFERENCE October 15-16, 2013 POWER SESSION The Case for Simplicity By Sean M. Hickey Loch Caillte Consulting

3 Abstract With a personal perspective beginning in 1977 with the design and construction of DP drilling rigs, DP construction vessels, and DP support vessels, the author will contrast the levels of complexity in state of the art diesel electric power systems against his experience with diesel hydraulic systems. The paper will address the technical issues, cost issues and the human aspects with a focus on developing world markets.

4 Sound Bites My Mantra: Solutions should be elegant in their simplicity. Dr. Stanbery s three engineering criteria: It should work fine, fail safe, and last a real long time.

5 Introduction This paper is about simplicity. It deals with dynamic positioning only. It does not deal with mission equipment or the power systems required for mission equipment. What I intend to do is layout a simple robust dynamic positioning philosophy. This philosophy is appropriate for a drilling vessel, a pipelayer, a crane vessel, an accommodation unit, or a rocket launch platform. The idea for this paper came from two conversations at the end of February The first of these conversations was initiated by a request for input on experience with power management and generator controls from competing vendors. The second was an inquiry from an owner who had been asked by his Naval Architect why we didn t take his Thrustmaster OD2000 portable thrusters apart then replace the couplings, gears, and pumps with electric motors, a parallel switchboard and generators on the engines.

6 Conversion Projects Chickasaw Two 750 HP Retractable Thrusters, HPUs Hull Mounted Titan 2 Eight 1000 HP Swing Down Thrusters, HPUs Containerized Truong Sa (ex Titan 1) Eight 2000 HP Swing Down Thrusters, HPU s Containerized McDermott DB30 Eight 2000 HP Retractable Thrusters, HPUs Hull Mounted Titan 3 & 4 Under Negotiation

7 DYNAMIC POSITIONING CONFERENCE September 17-18, 2002 Power Maintaining Full Station Keeping Capabilities During a Blackout Keith Hebert Global Industries, Ltd., Carlyss, Louisiana

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14 The Diesel Electric Perspective Beginning with the SeDco 445 in 1971, the first DP drilling vessels adopted diesel electric propulsion plants for a number of reasons including: Electrically driven thrusters were controllable. The power plants were scalable. They had an arguable level of redundancy. At the time microprocessors were new to the market. Components in generator controls, switchboards, SCR systems, shipboard I/C systems, etc. were primarily analog electronics or electrical devices. Digital controls were in their infancy.

15 The Evolution of Diesel Electric Pre-regulation Switchboard 1977 Buss Links DP2 Switchboard 1994 One Tie Breaker DP3 Switchboard 1994 Two Tie Breakers Enhanced Reliability Ring Buss 2011/12 Eight Tie Breakers

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23 The Diesel Hydraulic Perspective McDermott DB30 Eight 2000 HP Retractable Thrusters Water Cooled Mounted in existing sponsons 14 Hydraulic Lines Shipboard Piping Fuel fill and return Cooling water Shipboard Electrical Cables 2 CAN Buss 1 Six conductor 2 Power (Battery Charger & Emergency Retraction Pump)

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29 REAR VIEW FRONT VIEW

30 HYDRAULIC POWER UNITS

31 Regulatory Complexity and Bias As systems have become more complex, the regulatory environment has also become more complex. Beginning with a single sentence in IMO Resolution A.649(16), DP regulations can now be measured by the pound of paper it requires to print them. Resolution A.649(16) 19 Oct Dynamic Positioning systems Dynamic positioning systems used as a sole means of position keeping should provide a level of safety equivalent to that provided for anchoring arrangements to the satisfaction of the administration. MSC 38.(63) 19 May 1994 *Reference is made to the Guidelines for Vessels with Dynamic Positioning approved by the Maritime Safety Committee at its 63 rd session and disseminated by MSC/Circ IMO MSC June pages DNV DYNPOS ER Jan pages ABS EHS December pages

32 Enhanced Reliability In the recent past, both ABS and DNV have introduced new classifications for vessels design with Enhanced Reliability. Per Section 8 Table 1 of the ABS Guide for Dynamic Positioning Systems and the Part 6 Chapter 26 Section 5 of the DNV rules for ships, the new classifications would appear to apply only to diesel electric propulsion. While there was a clear need for the regulatory bodies to catch up to the state of the art in diesel electric systems, there is an implicit bias toward the use of diesel electric power systems over any other form of propulsion. My contention is that this contributes to the That s how DP2 works. mindset.

33 Gedankenexperiment (A Thought Experiment) Convert an ENSCO 8500 to Diesel Hydraulic

34 Ensco North & South America Katy Freeway Suite 300 Houston, TX Phone: Fax: ENSCO 8500 GENERAL INFORMATION Flag Liberian Previous Name(s) _ Year Built 2008 Builder KFELS - Singapore Design Dynamically Positioned DP-2 Classification A. B. S. Maltese Cross A1 column stabilized drilling unit MAIN DIMENSIONS Pontoons 56' x 24' x 310' Moon Pool 30' x 120' Columns 50' x 45' Keel to Main Deck 97' 0" Main Deck 240' W x 255' L MACHINERY Main Power (7) EMD series ME20-710G7C - 5,000 (Marine/Continuous) BHP/each; (7) Baylor S855YNV - 643, 3,580 KW generators Power Distribution NOV-ABB, 25.1 MW, 4,160-volt main power generation distributed through transformers for marine and drilling functions Emergency Power (1) Cat 3512B, 1,476 HP Thrusters (8) Flowserve Pleuger WFDS , 3,500 HP/each OPERATING PARAMETERS Water Depth 8,500' Maximum Drilling Depth 35,000' Air Gap 55' drilling draft Transit Speed ' draft Variable Drilling Loads 8,000 t Operating Conditions 8,000 s. 55' Survival Conditions 8,000 s. 45' Transit Conditions 5,800 s. 25 DRILLING EQUIPMENT Derrick NOV 201' x 46' x 40'; 2,000,000 lb static hook load Drawworks NOV ADS-30Q, 6,000 HP, 2" Drill Line Rotary NOV RST 605 hydraulic, 60 1/2 opening, 1,000 ton Top Drive NOV-TDS-1000 (1000 ton) 7,500 psi, GEB-20B 1150 HP (AC Motor), PH-100 Drill String Compensator NOV, CMC-H , 1000K Travelling Block NOV HTB 7-72TB-1000, 1,000 ton Pipe Handling NOV-BR-15 Bridge Racker with Z-Back racking guide arm 3 1/2" - 22", HTV machine up to 22", PR-45-90HS Catwalk machine, AR4500 & ST-120 iron roughnecks, PS30 slips, BX4 & BX5 elevators, 1 x 45' & 1 x 60' telescopic foxholes Cementing Haliburton HCS Advantage Mud Pumps (4) Lewco, W-2215, 2,200 HP, 7,500 psi

35 A Diesel Hydraulic DP2 ENSCO 8500 Existing thrust: 8 x 3,500 HP = 28,000 HP Worst case DP2 failure as is leaves: 4 x 3,500 HP = 14,000 HP Converted thrust: 8 x 3000 HP = 24,000 HP Worst case DP2 failure converted leaves: 7 x 3000 HP = 21,000 HP An 8.57% reduction in installed power gives a 50% increase in single point failure holding capability.

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37 What Did I Do? I lost 8 each switchboard cells, transformers and VFDs. I lost eight AC motors, and all the required auxiliaries including MCC s to drive fans, cooling water pumps, thruster steering gear, etc. I lost miles of cable, cable hangers, and associated penetrations. I cleaned the main deck off by reducing the generation requirements and, therefore, the engine room and switchgear room size. At the same time I lost piping diameter and pump capacity required to cool the mission equipment generation. I lost weight, equipment cost and construction cost. Losing weight and moving the thruster HPU s to the column flats, I gained deck space, deck load and improved my VCG. Bonus!!!! I am DP3 Compliant.

38 A Diesel Hydraulic DP3 ENSCO 8500 Existing thrust: 8 x 3,500 HP = 28,000 HP Worst case DP2 failure as is leaves: 4 x 3,500 HP = 14,000 HP Converted thrust: 8 x 3000 HP = 24,000 HP Worst case DP2 failure converted leaves: 6 x 3000 HP = 18,000 HP An 8.57% reduction in installed power gives a 29% increase in single point failure holding capability.

39 But isn t diesel electric more efficient? Is it? Since this is a paper about simplicity, here is the simple answer; It s all voodoo, like federal deficit predictions. We know the BTU s in a given volume of MDO. We know that the torque is imparted to the water at the propeller tip. We know that the BTUs in the MDO are converted into torque at the flywheel by the diesel. We know there are efficiency losses in any means of transmission for that torque to the propeller tip. Making a bunch of assumptions we can calculate the losses in any form of transmission. What we don t know is the amount of torque we need for a given unit of time. In other words we cannot predict the environment. Consequently, all design points are based upon assumptions. It s kind of like predicting the federal deficit, voodoo.

40 Developing World Ocean News & Technology - August 2013, Page 37: Wood Mackenzie predicts huge deepwater drilling expenditure Over the next decade 95 new deepwater rigs 37,000 workers While there have certainly been advances in the delivery system for educational materials, no one has yet figured out how to deliver experience in any really new and creative way. There will be pressure from local governments to employ nationals. Educated and more importantly experienced locals are not going to just appear. They will have to be developed. The more complex the systems we produce, the more risk we face.

41 Conclusion As with my initial reaction to diesel hydraulic propulsion systems, my reaction to early DP supply designs using shaft generators was extremely negative when I first encountered them. The same was true of my opinion of direct drive diesel boats. In both cases I thought they should just build a diesel electric boat. Having had the opportunity to survey Chouest and Harvey Gulf vessels I recognize the virtues of these designs. As they have evolved, they have become simple, robust and appropriate to the their missions. There is a tendency for all of us to be predisposed to doing things the way we first learned how to do them. My father drove Chevy s, so I know that Chevy s are the best car. I learned how to build diesel electric DP vessels from my mentors and peers, so I know, That s how DP2 works. At least I used to know that. I now know better. I know that simpler is better.